Sheet material



, United States Patent SHEET MATERIAL Ernest A. Rodman, Newburgh, N. Y.,assignor to E. I; du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware No Drawing. Application October 1, 1954, SerialNo. 459,839

Claims. (Cl. 154-101) This invention relates to non-woven sheet materialand, more particularly, to such materials wherein matted polymericlinear terephthalate ester fibers are bound together by a polymericdiisocyanate elastomer.

Various types of fibers and binders have been employed in theconstruction of non-woven fibrous sheets for a variety of uses. Manyattempts have been made to duplicate the appearance and properties ofleather. Usually when the appearance is achieved one or more of theproperties such as water vapor permeability, flex life, abrasionresistance, and tensile strength are not present, and vice versa.

The primary object of this invention is to provide a new sheet materialof the type in which matted polymeric linear terephthalate ester fibersare bound together with a polymeric diisocyanate elastomer. A furtherobject is the provision of a sheet material which has the appearance ofleather combined with the properties of leather. A still further objectis to provide a leather replacement product having a degree of watervapor permeability comparable to that used in shoe uppers. A stillfurther object is the provision of a non-Woven sheet material havinghigh abrasion or scuff resistance. A still further object is theprovision of porous paperlike products. Other important objects will beapparent from the description of the invention given hereinafter.

The above objects are accomplished according to the present invention byforming a sheet material comprising a batt of polymeric linearterephthalate staple filaments bound together with a polymeric elastomerobtained by reactions involving a polyalkyleneether glycol having amolecular weight of at least 750, an organic diisocyanate and achain-extending compound containing active hydrogen atoms, such as, e.g., water, hydrogen sulfide or an organic compound containing activehydrogen atoms attached to two diiferent atoms in the molecule. Thepolymeric elastomers and their preparation are fully described'incopending application Serial No. 365,270, filed June 30, 1953, by F. B.Hill, Jr.

Throughout the specification and appended claims the term polymericlinear terephthalate ester fibers refers to highly polymerized linearester fibers of terephthalic acid and a glycol of the series HO(CH2)nOH,Where n is a whole number within the range of 2 to 10, inclusive. Thepolymeric linear terephthalate ester fibers may be prepared inaccordance. with the teaching set forth in U. S. Patent 2,465,319,issued March 22, 1949, to J. R. Whinfield et a1.

Throughout the specification and claims the terms fiber and filament areused synonomously and embrace both staple and continuous filaments.

The high strength and suppleness of the sheet material produced inaccordance with this invention depends to a large extent on the affinitybetween the polymeric linear terephthalate fibers and the abovementioned polymeric elastomer binder. When the degree of adhesionbetween the fiber and binder is too great the fibers are cementedtogether in such a manner that they maybe broken one 2,723,935 PatentedNov. 15, 1955 at a time when a stress is applied, which results in lowtear strength. If the degree of adhesion between fiber and binder is toolow a high tensile strength sheet material is not realized. The degreeof adhesion between the polymeric linear terephthalate fibers andpolymeric elastomer binder is such that products of this invention areflexible and have both high tear and tensile strengths.

The batts of polymeric linear terephthalate fibers may be prepared by avariety of techniques, such as, e. g., paper making technique, carding,deposited from air stream or any suitable web forming apparatus.

The following specific examples are given by way of illustration and notlimitation. Throughout the specification and appended claims the partsand percentage figures are expressed on a weight basis.

Example 1 A fluffy loosely bound batt of .1 denier 1.25 inch staplepolyethylene terephthalate fibers, weighing about 6 ounces per squareyard, was formed on a card. The batt was immersed in a 3% solution of apolytetramethyleneether glycol/toluene diisocyanate elastomer indimethyl formamide. The excess solution was pressed from the batt, thendried at about 200 F. Upon drying, the fibers became compacted and thedried material was a fibrous leather-like sheet. There was a tendencyfor the elastomer to migrate toward the surface of the sheet on drying,thus the ratio of binder to fiber was greater in the surface portion ofthe sheet than in the middle portion.

The polytetramethyleneether glycol/toluene diisocyanate elastomeremployed in the above example was prepared by mixing together in aWerner-Pfleiderer mixer at 7080 C. for 3 ]1ours one molar proportion ofa polytetramethyleneether glycol of molecular weight of 3230 and 2.1molar proportions of 2,4-tolyl ene diisocyanate. Then 5.11 molarproportions of water were added and mixing was continued for 33 minutes,the temperature rising to about 135 C. At the end of this time thereaction mass was in the form of rubbery chunks. It was removed from themixer and put on a rubber roll mill where 0.74 part of piperidene wasadded for each 100 parts, by weight, of the polymer. When thoroughlymixed, the stabilized elastomer was sheeted oif the mill.

The ratio of fiber to hinder (elastomer) throughout the entire sheet was1.0 to 1.2. The LPV (leather permeability value) was 1000 at 78 F. andrelative humidity when tested in accordance with the procedure describedhereinafter. The fibrous sheet withstood 1,500,000 flexes on theSchiltknecht flex apparatus before the first surface crack appeared.

The product was highly abrasion resistant. The surface could not bemarred by over 50 hand scrapes using a ten cent coin as the scrapinginstrument. The products of this invention do not lend themselves to thestandard abrasion tests such as the Wyzenbeek test described in FederalSpecification CCC-T-191b, dated May 15, 1951, Method 5304, since theyare uniform throughout and there is no definite end point encountered bysuch abrading apparatus, as in the case of a coated fabric where the endpoint is taken when the coating is abraded through to the fabric. i

Example 2 A fiuify loosely bound batt of .1 denier 1.25 inch staplepolyethylene terephthalate fibers weighing 10 ounces per square yard wasformed on a card. The batt was immersed in a 5% solution of apolytetramethyleneether glycol/toluene diisocyanate elastomer (same asin Example 1) in dimethyl formamide. The batt was pressed to remove theexcess solution. The batt was then subjected to live steam to coagulatethe polymer uniformly throughout the batt before it was dried at 250 F.

Up drying, he fibe became compacted and t e resulting material was afibrous leather-like sheet in which the binder was substantially equallydistributed throughout the sheet.

The ratio of fiber to binder was 1 to .8. The dried product had an LPVvalue of 5000 when tested at 78 F. and 90% relative humidity. There wasno apparent failure in the material after 10,000,000 flexes on theSchiltknecht flex apparatus.

Example 3 Ten parts of carbon black were milled into 100 parts ofapolytetramethyleneether glycol/toluene diisocyanate elastomer (same asExample 1) on a two-roll rubber rnill. Example 2 was repeated using a 5%solution of e m l ed e st mer n di ethyl f rmami e as the bind r n p eof that d scr bed in Example 2- The dried product of this examplediffered only from that in Example 2 in that it had an LPV value of 6000and was black.

Example 4 A leather. replacement product was made in accordance with thefollowing continuous procedure: Polyethylene ter e phthalate .1 denierfiber 2.5 inches long was fed to a card Where a flulfy batt weighing 8ounces per square yard was continuously formed. The batt wascontinuously plied to form a two ply batt weighing 16 ounces per squareyard. The two ply batt was continuously passed through a needle loom togive the batt added strength.

A suitable needle loom is illustrated in copending application, S. N.312,067, filed September 29, 1 952 by H. G. Lauterbach. From the needleloom the batt was continuousiy passed through a heat zone at 300 F; toefiect about 15% shrinkage in the area of the batt. The batt 'the waterand dimethyl formamide. The impregnation and, subsequent drying stepscompact and; consolidate the batt without the application of anypressure treatments to formv a leather-like sheet material. The dryimpregnated leather-like. sheet material was then continuously butfed onone side with a 2 401 emery covered roll to provide a smooth surface.was then continuously spray-coated: on the buffed side with thefollowing composition:

Parts by weight 50% aqueous latex of a copolymer of butadiene andacrylonitrile 36% aqueous solution of a phenol/formaldehyde resin 30.37.5% aqueous solution of sodium polyacrylate 9.1

About 1.0 dry ounceof spray coat-was applied per square yard. The spraycoated sheet was continuously dried by passing through a heat zone andwhile hot it was next em bossed by pressing between coldpressure plates,one of which was steel and had a leather design engraved on its surface.7 I l The polytetramethyleneether glycol/toluene diisocyanate elastornerused in this example was prepared. as follows: Three mols, ofpolytetramethyleneether glycol of molecular weight 920 containing 0.02mol of water is mixed with 2.02 mols of 2,4-tolylene diisocyanate at 100C for 3 hours. A polyurethane with, terminal; hydroxyl groups. and amolecular weightofi 3,110 is formed. 311 parts of this polyurethane and0.57 part of water are The smooth surfaced sheet m xed. in a er -P e r rxer at f 10 minutes and then parts of 2,4-tolylene diisocyanate is addedand the mass is mixed at -75 C. for 2.5 hours. To the viscous reactionmass is added 12.6 parts of water and mixing is continued for 30 minuteswhile the temperature increases from 70 to C. The rubbery polymer isdischarged from the mixer and put on a rubber roll mill where 0.7 partof piperidene per 100 parts of polymer is added for stabilization. Afterthorough mixing of the stabilizing agent, the elastorner is sheetedoff-the mill.

The leather replacement product of this example had the appearance, feeland texture of leather such as used in shoe uppers. The ratio of fiberto hinder was 1 to .5. Physical properties were:

Total weight 20.0 oz./ sq. yd. Leather permeability value 3000. Tensilestrength1" strip (avg) 87 lbs. Tear strength (ASTM,

1162 4-48, die C) 22 lbs/inch. (Comparable to leather used for shoemanufacture.)

The product was useful as a replacement for the leather in shoe uppers.Mens shoes made with the product of this example. as the uppers had anacceptable comfort value with respect to moisture transmission.

Example 5 A laminated assembly was prepared by carding a batt of heatshrinkable 0.1 denier 1.25 inch staple fibers of polyethyleneterephthalate weighing .5 ounce per square yard. The batt wasimpregnated with a 10% solution of the polytetramethyleneetherglycol/toluene diisocyanate elastomer, described in Example 1, indimethyl formamide and then heated to dry the batt. The batt picited upits own weight of dry elastomer. Eight separate plies 0f the impregnatedbatt were then superposed and subjected to a pressure of 750 p. s. i. at300 F. for 3 minutes. The ratio of binder to fiber was 1:1 and thelaminated assembly Weighed 8.0 ounces per square yard.

The product had a fibrous leather-like structure.

Example 6 LPV' 2660. Gurley-a-ir porosity .59 cc./sec. Thickness 40mils. Tensile strength2" strip. 240 lbs. Tea-r strength (ASTM, D625-48,

die C) 53.5 lbs/inch.

Low temperature-Gurley at zero 2.10 greater than at -F room temperature.Schiltknecht flex, surface OK at--. 10,000,000 flexes.

The product was. useful for shoe uppers.

Example 7 A fluify batt of 3.0 denier, 1.5 inch staple of polyethyleneterephthalate fibers Weighing six ounces per square yard was formed on acard. The batt, was subjected to a dry temperature of 300 F. for twominutes which. shrunk the. batt 25 in area, and; compacted. the batt,The eat. hr nk. tt, w s mmersed. n the. fo low.- ing composition: a

greases Parts by weight Polytetramethyleneether glycol/toluenediisocyanate elastomer (same as Example 1) 9.4 Toluene diisocyanate urea.6 Dimethyl formamidenu 90.0

substrate for surface coatings.

Example 8 The following ingredients were mixed on a two roll rubber millin accordance with the well known procedure employed in the rubberindustry. 1

i Parts by weight Polytetramethyleneether glycol/toluene diisocyanateelastomer (same as in Example 1) 100 Carbon black -1 50 Toluenediisocyanate urea 4 The toluene diisocyanate urea serves as acrosslinking or curing agent for the elastomer. After. thorough mixingof the above ingredients they were sheeted out in the form of a film2.5-3.0 mils thick, weighing about 3.0 ounces per square yard. A mixtureof three parts of,3.0 denier, 1.5 inch staple polyethylene terephthalatefibers and one part of 3 denier, 1.5 inch staple viscose/rayon fiberswere blended and carded into a batt weighing about 3.0 ounces per squareyard. A composite assembly was formed of three layers of film andthreelayersof the batt arranged in the following order:

Batt

First layer Second layer Film Third layer 1 r Batt Fourth layer FilmFifth layer..- Batt Sixth layer Film The assembly of alternating layersofbatt and film were subjected to a pressure ofabout 600 p. s. i., at275 F. for about 30 minutes to cure the elastomer. The. separate layerswere welded together to form a composite unitary structure having asmooth skin of elastomer. on one side and a'fibrous surface on the otherside. The laminated assembly had the following physical properties:

Total weight l8.3.oz./sq. yd; Thickness 22 mils. Schiltknecht flex,surface OK at 1,000,000 flexes. Leather vapor permeability 1640.

Gurley-air porosity (20 oz. cylinder) 0.

The product had the appearance of calf skin leather. It was particularlyadapted for fabricating ladies pocketbooks. Other useful products canbemade with only one layer of the batt and only one layer of the film.

Example 9 A porous paper-like structure was prepared by impregnati'ng awaterleaf of polyethylene terephthalate'fibers with a 10% solution of anelastomeric polymer described more fully below. Polyethyleneterephthalatestaple fibers Vs inch in length, three denier per filament,were formed into a waterleaf by making a slurry of the fibers in waterand then forming into sheets weighing 2.0 ounces per square yard byconventional paper making techniques. The waterleaf was dried and thenimpregnated by dipping into a 10% solution of an elastomeric polymer incarbon tetrachloride. The elastomeric polymer was the reaction productof 3 mols of polytetramethyleneether' glycol and 2 mols of 2,4-tolylenediisocyanate to form polyurethane, which in turn. was reacted with 0.32mol of water and 2.3 mols of 2,4-tolylene diisocyanate. The excesssolution was allowed to drain from the waterleaf and then the volatilecomponent of the impregnating composition was allowed to evaporatealmost completely and then the polymer was coagulated by soaking thesample in 5% solution of dimethylpiperazine in methanol, followed bythorough washing with water. The drying of the impregnant concentratesthe elastomeric polymer at the fiber cross-over points producing aporous structure.

The final product had the following physical properties:

Fiber/binder-weight ratio 1: 1.6

Bursting strength (p. s. i.) 102 Elmendorf tear strength (grams) 554Thickness (mils) 25 The product was flexible, having the appearance andsurface characteristics of blotting paper. It was ideally suited as astiffener for wearing apparel in the construction of mens jackets. Itwas also suitable for fabricating into ladies petticoats which give aflare to outer garments.

Polytetramethyleneether glycol is the preferred glycol for reacting withthe 2,4-tolylene diisocyanate to prepare the polymeric elastomers usefulin carrying out this invention. Other polyalkyleneether glycols whichare representative of the class which may be used. in preparing thepolymeric elastomers include polyethyleneether glycol,polypropyleneether glycol, polybutyleneether glycol, 1,2-polydimethyleneether glycol and polydecamethyleneether glycol.

The term polyalkyleneether glycol, as used throughout the specificationand claims refers to polyalkeneether glycols containing terminal hydroxygroups. These compounds are ordinarily derived from the polymerizationof cyclic ethers such. as alkylene oxides or dioxolane or from thecondensation of glycols. They are sometimes represented by the formulaHO(RO)nH, in which R stands for an alkylene radical and n is an integergreater than 1. In the polyethers useful in preparing the polymericelastomers of this invention, i is suificiently large that thepolyalkyleneether glycol has a molecular weight of at least 750 and maybe as high as 10,000. Polyalkyleneether glycols having a molecularweight of 750 to 3500 was preferred. Not all the alkylene radicalspresent need be the same. Polyglycols formed by the copolymerization ofa mixture of different alkylene oxides or glycols may be used, or thepolyglycol may be derived from a cyclic ether such as dioxolane, whichresults in a product having the formula HO(CH2OCzH4)nH. Examples ofcompounds which contain diverse alkylene radicals and which are usefulin the preparation of elastomers are those polyethers described inUnited States Patent No, 2,492,955 to Ballard et al. which havemolecular weights in the desired range. The alkylene radicals may bestraight-chain or may have a branched chain as the compound known aspolypropyleneether glycol, which has the formula Any of a wide varietyof organic diisocyanates may be employed in preparing the polymericelastomers of this invention including aromatic, aliphatic andcycloaliphatic diisocyanates and combinations of these types.Representative compounds include'2,4-tolylene diisocyanate, m-phenylenediisocyanate, 4-chloro-l,3-;phenylene diisocyanate, 4,4'-biphenylenediisocyanate, 1,5-naphthylehe diisocyanate, 1,4-tetramethylenediisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylenediisocyanate, 1,4-cyclohexylene diisocyanate,4,4-methylene-bis-(cyclohexyl isocyanate) and 1,5-tetrahydronaphthylenediisocyanate. Arylene. diisocyanates, i. e., those in which each of thetwo isocyanate groups is attached directly to an aromatic ring,are'preferred. In general they react more rapidly with thepolyalkyleneether glycols than do the alkylene diisocyanates. Compoundssuch as 2,4-tolylene diisocyanate in which the two isocyanate groupsditfer in reactivity are particularly desirable. The diisocyanates maycontain other substituents, although those which are free from reactivegroups other than the two isocyanate groups are ordinarily preferred. Inthe case of the aromatic compounds, the isocyanate groups may beattached either to the same or to different rings. Dimers of themonomeric diisocyanates and di(isocyanatoaryl) ureas such asdi(3-isocyanato-4-methylphenyl) urea, which are the subject of U. S.application Serial No. 365,280, filed June 30, 1953, by Eric Barthel,Jr., may be used.

The leather permeability values were carried out by filling a three inchdiameter crystallizing dish with 12 mesh calcium chloride, covering thedish with membrane of the substance to be tested and placing the covereddish in an atmosphere of high humidity (23 C. and 90% relativehumidity). The assemblage is weighed at intervals and the equilibriumrate of sorption is recorded as grams of water per 100 sq. meters ofsurface per hour which is the leather permeability value. This is amodification of a test developed by the Bureau of Standards, Kanogy &Vickers, J. Res. Nat. Bur. of Std., 44, 347-62, 1950 (April).

The Schiltknecht flex test was carried. out on apparatus described inBulletin No. 105 of Alfred Suter, 200 Fifth Avenue, New York city, N. Y.

The small denier fibers (less than 1.0 denier per filament) may beprepared by superstretching the polymeric linear terephthalate esters inaccordance with the procedure described in U. S. Patent 2,578,899,issued December 18, 1951, to A. Pace, Ir. There is no particular lowerlimit for the denier of the polymeric linear terephthalate fibers usefulin this invention other than the ability to make fibers of extremely lowdenier. Fibers having a diameter of .1 micron 0.00008 denier perfilament) may be usedv in practicing this invention. Filaments having :adenier greater than 1.0 denier per filament result in sheets which havepoor scuff resistance in comparison to leather.

For leather replacement products which require high scufi resistance,fine denier fibers, i. e. less than 1.0 denier per filament arerequired. For other uses. such as, e. g., substrates for flexiblesurface coatings and paper-like products much higher denier fibers maybe employed. There is no particular upper limit for the denier of thepolymeric linear terephthalate fibers for products which do not requirehigh scuff resistance. Fibers having a denier of 50 to 70 produce usefulnon-woven fabrics, and where extremely coarse felt is desired, even.coarser filaments having a. denier of 1.00 to 150 maybe used. The fibermay be straight or crimped.

The ratio of fiber to binder in the various examples varies between 1.0to .5 and 1.0 to 1.6. While this represents. the preferred range, usefulproducts can be prepared where the ratio of fiber to binder is between1.0 to .3 and 1.0 to 2.0.

The non-woven webs of this invention may be surface coated with watervapor transmittable coatings such as described in copending applicationS. N. 439,900, filed June, 28, 19 54,. by R. J. Mayfield and S. N.337,671, fi led February 1.8, 1953; S. N. 337,672, filed. February 1 8,1953; and S. N. 364,487, filed June 26, 1953, by'H, L. Jackson.

In place of the polyethylene terephthalate fibers used in, the specificexamples, it. is to be understood that the highly polymerized estersobtained by the reaction of terephthalic acid and polymethylene glyeolshaving more than. 2 but not' more than: l-O methylene groups may alsobeused'. in carrying'out. this; invention; suclr as, e. g. trimethylene:glycol, tetramethylene glycol, pen-tamethylene glycol; heptametliylene:glycol, octamethylene glycol,

monomethylene' glycol and decamethylene glycol; the glycols having 2m 4methylene groups are preferred.

While the relative thickness (denier) of the fibers is an importantconsideration in practicing this invention, the length of the fibers isnot critical and they can vary from as little as .01 inch up to 8 inchesin length or greater. The fiber length is determined primarily by themethod of preparing the batt of fibers. For instance, if the batt isprepared by paper making techniques, fibers no longer than about .5 inchare employed. Batts prepared by air-blowing techniques and web makingapparatus as described in U. S. Patent 2,451,915, issued October 19,1948, to Francis M. Buresh, employ fibers not greater than about 1.5inches in length. Batts' of fibers of 1.5 inch length and greater arepreferably prepared on carding machines.

As illustrated by Example 8, mixtures. of polymeric linear terephthalatefibers and dissimilar fibers may be employed in practicing thisinvention. When a mixture of fibers is employed the polymeric linearterephthalate fibers should be present in a predominating proportion.Other fibers which may be blended with the polymeric linearterephthalate fibers include nylon, polyacrylonitrile, cotton, wool,glass, and viscose rayon fibers.

The batts. of polymeric linear terephthalate may be brought in contactwith the polymeric diisocyauate elastomer binder in a variety of ways,such as impregnating the batt with a solution or dispersion of thebinder or simple mixing where the binder in particulate form is broughtin contact with the fibers. When the binder is added as a dispersionordry particles heat and pressure are required to bring about coalescenseof the binder. Also, preformed films of the polymeric diisocyanateelastomeric binder may be brought in contact with the batts of polymericlinear terephthalate fibers.

In the examples dimethyl formamide is used as the solvent for dispersingelastomeric binder to form the impregnating medium. The compoundeduncured elastomers used in this invention may be dissolved in othersolvents to form the impregnating composition. The action of solventsappears to be quite specific and varies from one elastomer to. another.The uncured reaction product made from a polytetramethyleneether glycol,2,4- tolylene diisocyanate and water will form a dispsersed free flowinggel or solution in concentrations of 5 to 10%, by weight, in I dimethyl,formamide, tetrahydrofuran, methyl ethyl ketone, toluene, nitrobenzene,o-dichlorobenzene, tetrachloroethane, chloroform, thiophene, a 50/50mixture of tetrahydrofuran and methyl ethyl ketone, a 50/50 mixtureoftetrahydrofuran and benzene, plyridiine,'cyclohexanone, and the diethylether of ethylene g yco Color can be imparted to the sheet material ofthis invention by incorporating dyes or pigments in the poly mericbinder, or by dyeing the batt or using pre-dyed or pre-pigmented fibers.Preferably, color is added by dyeing the batt of fibers.

An advantageof this invention isthat it provides sheet material having.great scutf resistance combined with water vapor permeability, high.tensile and tear strengths and satisfactory flex-life.

The products of this invention are useful as leather replacements in themanufacture of ladies handbags, mens and ladies jackets, belts, shoeuppers, protective clothing, luggage,,upholstery,, bookbindiug andnovelties.

While; there are above disclosed. but a limited number of. embodimentsof the structure, process and product of the invention herein presented,it. is possible to produce stillother. embodiments without departingfrom the inventive concept herein disclosed, and it is desired there-.fore that only; such limitations be imposed on the apprising polymericlinear terephthalate ester filaments bound together with the polymericreaction product of a polyalkyleneether glycol, an organic diisocyanateand a chain extending compound containing active hydrogen atoms.

2. The product of claim 1 in which the ratio of filaments to binder iswithin the range of 1 to .3 and 1 to 2.0.

3. The product of claim 1 in which the polymeric linear terephthalateester is the ester of terephthalic acid and a glycol having theempirical formula Where n is a whole number within the range of 2 to 4,inclusive.

4. The product of claim 1 in which the polymeric linear terephthalateester is polyethylene terephthalate.

5. The product of claim 1 in which the polyalkyleneether glycol has amolecular weight of 750 to 10,000.

6. The product of claim 1 in which the polyalkyleneether glycol has amolecular weight of 750 to 3500.

7. The product of claim 1 in which the binder is the polymeric reactionproduct of one mol polytetramethyleneether glycol, 2.1 mols of2,4-tolylene diisocyanate and 5.11 mols of Water.

8. The product of claim 1 in which said polymeric reaction product iscross-linked with toluene diisocyanate urea.

9. The product of claim 1 in which substantially all the filaments havea denier less than one.

10. The product of claim 1 in which the ratio of binder to filaments isgreater in the surface portion of the sheet than in the middle portion.

11. The product of claim 1 in which the binder is substantially equallydistributed throughout the sheet.

12. The process of preparing non-woven sheet material comprising forminga batt of loosely bound polymeric linear terephthalate ester filaments,distributing throughout said batt the polymeric reaction product of apolyalkyleneether glycol, an organic diisocyanate and a chain extendingcompound containing active hydrogen atoms, heating and pressing the battto consolidate the filaments and said polymeric reaction product into aunitary structure.

13. The process of claim 12 in which the polymeric linear terephthalateester filaments are polyethylene terephthalate.

14. The process of claim 13 in which the polymeric linear terephthalatefilaments are less than one denier per filament.

15. The process of claim 12 in which the polymeric reaction product isthe reaction product of one mol of polytetramethyleneether glycol, 2.1mols of 2,4-tolylene diisocyanate and 5.11 mols of water.

16. The process of preparing non-woven sheet material comprising forminga batt of loosely bound poly meric linear terephthalate ester fibers,needle punching the batt, heating the batt to cause the fibers toshrink, impregnating the shrunken batt with a solution of the polymericreaction product of a polyalkyleneether glycol, an organic diisocyanateand a chain extending compound containing active hydrogen atoms in avolatile watersoluble organic solvent, treating the impregnated battwith Water before the volatile organic solvent is evaporated, heating toevaporate the organic solvent and Water, subjecting the dry impregnatedbatt to heat and pressure, buifing at least one side of the dryimpregnated batt to remove the protruding portions of fibers, andcoating the buffed side of said sheet with a water vapor transmittablecoating.

17. The process of preparing non-Woven sheet material comprising a battof loosely bound polyethylene terephthalate ester fibers, needlepunching the batt, heating the batt to cause it to shrink, impregnatingthe shrunken bat with a solution of the polymeric reaction product ofone mole of polytetramethyleneether glycol per 2.1 mols of 2,4-tolylenediisocyanate and 5.11 mols of water, and toluene diisocyanate urea, in avolatile water-soluble organic solvent, treating the impregnated battwith water before the volatile organic solvent is evaporated, heating toevaporate the volatile components, and subjecting the dry impregnatedbatt to heat and pressure.

18. The process of preparing a laminated assembly comprising forming anon-woven batt comprising polymeric linear terephthalate fibers,separately preparing a film comprising the reaction product of apolyalkyleneether glycol, an organic diisocyanate and a chain extendingcompound containing active hydrogen, and toluene diisocyanate urea,superposing at least one layer of said film on at least one layer ofsaid batt, subjecting the superposed layers to heat and pressure to forma unitary structure.

19. The process of claim 18 in which said polymeric linear terephthalateis polyethylene terephthalate.

20. The process of claim 18 in which said reaction product is thereaction product of one mol of polytetramethyleneether glycol, 2.1 molsof 2,4-tolylene diisocyanate and 5.11 mols of water.

References Cited in the file of this patent UNITED STATES PATENTS2,676,128 Piccard Apr. 20, 1954 2,689,199 Pesce Sept. 14, 1954 2,692,873Langerak Oct. 26, 1954 2,692,874 Langerak Oct. 26, 1954

12. THE PROCESS OF PREPARING NON-WOVEN SHEET MATERIAL COMPRISING FORMINGA BATT OF LOOSELY BOUND POLYMERIC LINEAR TEREPHTHALATE ESTER FILAMENTS,DISTRIBUTING THROUGHOUT SAID BATT THE POLYMERIC REACTION PRODUCT OF APOLYALKYLENEETHER GLYCOL, AN ORGANIC DIIOCYANATE AND A CHAIN EXTENDINGCOMPOUND CONTAINING ACTIVE HYDROGEN ATOMS, HEATING AND PRESSING THE BATTTO CONSOLIDATE THE FILAMENTS AND SAID POLYMERIC REACTION PRODUCT INTO AUNITARY STRUCTURE.